The first step in fixing the problem when a Fuel Pump is not building pressure is to identify the cause of the malfunction. Typically, a Fuel Pump maintains a pressure between 30 and 50 PSI, but failure to build pressure will result in poor engine start, acceleration, or stalling. One of the most common causes of low or no pressure is a clogged Fuel Filter that restricts fuel flow and causes the pump to fight. In fact, as many as 20% of Fuel Pump problems can be directly related to a clogged filter. To resolve this, the Fuel Filter should be replaced; this is usually easier and less expensive than replacing the entire pump.
If the filter is clean, the next thing is the Fuel Pump itself. A faulty Fuel Pump may not create enough pressure, normally due to a worn-out or damaged pump component. Most Fuel Pumps either wear out over time or get damaged by some kind of contaminant in the fuel. The result can be a low-pressure pump that might need to be completely replaced. The replacement cost for a fuel pump ranges from $400 to $1,000, depending on the make of the vehicle and labor costs. If the pump is still under warranty, this cost could be reduced or even free.
Moreover, inspect the Fuel Pump Relay and wiring connections for abrasion or damage. A faulty relay will not provide voltage to the pump, hence leading to its failure to pressurize the system. The relay is pretty simple to inspect using a multimeter for voltage measurement, and a faulty one can cost as low as $20 to replace.
In the event that the pump and filter are okay, and the relay is intact, the problem may be in the fuel lines or pressure regulator. The fuel line may be damaged, collapsed, and blocking the flow of fuel, while a lousy pressure regulator can’t maintain the correct pressure of the system. Replacement for fuel lines or pressure regulators can vary in price, from 100 to 500 dollars, depending on how complicated the system is.
This may be because of debris or rust in the tank of mostly older vehicles. These may block the intake of the Fuel Pump, which is why pressure drops. This could necessitate the cleaning or replacement of the tank itself, which costs in the range of $200 to $600, depending on the model and labor involved. If you have eliminated all of the above causes and the Fuel Pump is still not building pressure, it is probably time for complete pump replacement.